A Koi's health depends upon the environment provided by the human owner. Koi havea high resistance normally and succumb to disease usually only after exposure tostressful conditions that break down the normal immune system. A stressed fishbecomes a sick fish. It has been said that:
Stress is the main factor man has the most control over. Many disease causingorganisms normally occur in the same environment as the fish. They usually onlybecome a problem when present in significant quantities and/or stress occurs.Therefore, by controlling stress you can help maintain a healthy pond. Preventionis easier than treating your pond for disease. Some causes of stress are: Disease Agents: 1. Bacterial One of the principal causes of fish mortality is bacterial disease. Except for"columaris" nearly all bacterial infections occur secondarily to some otherprimary stress. Most are gram-negative organisms. Treatment: acriflavin,nitrofurans, oxytetracycline, kanamycin, chloramphenicol, sulfanomides, salt, etc. as a dip, topical, injection, or in feed. 2. Viral I know of no effective treatment except to remove nodular growths by scraping. 3. Fungal A secondary infection at the site of some other fish injury. Also affects damagedor disturbed fish eggs. Treatment: acriflavin, iodine, malachite green,methylene blue, salt, formalin as a bath, topical, or in pond. Most fish carry some parasites, but develop a degree of resistance that preventsproblems. On the other hand, parasites such as anchor worms and fish liceusually are a problem whenever present. Young fish are more susceptible toillness caused by parasites. Stress situations and/or seasonal climaticvariations may bring on infection. Some parasitic infections can be mistaken forbacterial diseases or viral infections and some may cause tumors. Treatment:Dylox, Masoten, Demilin, Formalin, Malachite Green, potassium permanganate orsalt in the whole pond or in a bath. Treating fish diseases is sometimes a haphazard affair because we do not alwaysexactly know what the fish is suffering from. It is not easy to make a correctdiagnosis and then, from that "guess," choose a medication and dosage. Treatmentsfor Koi diseases are still relatively unsophisticated. There are no fundsavailable in the U.S. for the development of ornamental fish medicine. Note: Dead fish decompose very rapidly and generally are of little diagnostic useeven if they have been frozen. It is better to have someone examine a live,diseased fish. Fish cannot be examined over the telephone! Methods of chemical treatment, (listed from most conservative to most drastic): Whole pond treatment advantages include apparent ease of administration and adesire to destroy all the harmful pathogens. The disadvantages are thatbiological filtration may be severely affected and drugs used in the treatmenttend to be absorbed by organic debris in the pond. In addition, therapeutic druglevels may not be reached as pond drug dosages are usually lower. External swabbing with antibiotics and/or disinfectants can be surprisinglyeffective. The disadvantage is that the fish is exposed to handling andpossibly anesthetics. Medication should be attempted after water quality and stress conditions havebeen improved. Partial water changes are very effective in improving waterquality and relieving stress. Beware of the problem of disease organisms that may be resistant to a particulardrug. Maintain a current listing of drugs that are effective. Acriflavin, forexample, is frequently used for shipping and handling of fish, and has beenabused to the point that strains resistant to this drug are not uncommon. Suggestions for a Koi first aid kit:
4. Parasitic
* Herwig Nelson: Handbook of Drugs and Chemicals Used in the Treatment of FishDiseases. Springfield, Illinois. Charles C.Thomas, Publisher.
For more information: Dr. Erik Johnson's Web Page.
Copyright © 2002, Richard L. Renshaw